Revert revision 1812758 "Update tests from Apache Commons IO 2.5 to 2.6." because commons-io requires java 7 and commons-email only java 6.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/email/trunk@1812768 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index f55176d..212bdf8 100644
--- a/pom.xml
+++ b/pom.xml
@@ -247,7 +247,7 @@
         <dependency>
             <groupId>commons-io</groupId>
             <artifactId>commons-io</artifactId>
-            <version>2.6</version>
+            <version>2.5</version>
             <scope>test</scope>
         </dependency>
     	<dependency>